1. Field of the Invention
The present invention relates to a decorative sheet, a method for producing the decorative sheet, an in-mold injection molding method using the decorative sheet, and a resin molded product obtained by the molding method.
2. Description of the Related Art
In various fields, designs are made or letters are written on the surface of resin molded products, and for doing this, a method of performing printing on the surface of resin molded products, a method of attaching a printed resin label to the surface, or the like is applied. Moreover, as a method for making designs having excellent durability on the surface of a 3D structure, an in-mold injection molding method, in which a decorative sheet having a design is disposed in a mold used for molding and then a molded product is formed by using a molten resin, is widely used.
In the in-mold injection molding method, a decorative sheet having a certain design is disposed in an inner wall of a hollow portion of a mold to be used for molding, injection molding is performed by supplying a molten resin from the gate of the mold, whereby the decorative sheet is integrally fixed to the surface of the molded product formed of the molten resin so as to make a design.
A decorative sheet is produced by providing an ink image by various methods such as printing or coating to the surface of a resin substrate suitable for molding and making a design. Considering the fact that the ink image is heated and stretched by in-mold injection which is performed after the above process, it is preferable for the ink image to have a certain degree of thickness, and from this point of view, screen printing is generally used as a printing method.
However, for screen printing, a printing plate needs to be produced, and for printing a small amount of images or for printing various images having similar designs changed partially, a more efficient method is required.
Recently, with the progress of ink jet recording techniques, an ink jet recording method has been used even for high-quality images, and a technique that applies, as an ink jet ink applicable to heat-molded products, an ink jet ink using an ultraviolet-curable ink composition containing cyclodextrin to decorative sheets and molded products has been suggested (for example, refer to JP2009-67860A).